Irradiated polymers



United States Patent Ofifice Patented Jan. 2%, W63

39,075,905 IRRADIAEED PQLYMERS Gaetano F. DAlelio, 2011 E. Cedar St., South Bend, Ind. No Drawing. Filed Earn. 6, 1958, Ser. No. 707,083 17 Qlahns. (til. Zed-154) This invention relates to improvements in linear, aliphatic, saturated polymeric esters. More specifically, it relates to the irradiation of such compositions, sometlr es hereinafter referred to as polymers or polymeric materials, in the presence of polyunsaturated modifiers, as defined hereinafter and sometimes herein referred to as modifier, and improved products obtained thereby.

In the past there have been certain limitations in the properties of saturated polymeric ester resins. In order to have solubility and low melting characteristics des rable for application of such resins for many purposes, such as coatings or shaped article, it has been necessary to sacrifice somewhat the solvent resistance and high melting point or heat resistance desired in finished articles made from these resins. Attempts have been made to effect improvements in such desired properties by incorporating in the resins substituents having unsaturation of a nature which might cause crosslinkages by post-treatmerit after application or shaping of the resin. However, difficulty in controlling the amount and the timing of such crosslinking and increased tendency of such materials to discolor have left much to be desired in that practice.

in accordance with the present invention, it has been found, however, that linear, aliphatic, saturated polymeric esters can be irradiated in intimate contact with polyunsaturated modifiers, as defined hereinafter to give products having improved properties, such as greater solvent and heat resistance and better strength characteristics than the original polymer had. Furthermore, these irradiated products can be hydrolyzed or saponified to give materials or monomeric units different from those of which the polyester resins were originally constituted.

The polyunsaturated modifiers used in the practice of this invention have the formula:

R l CHg=(E(CR"2)0n-OZO (CR"2)o-nC=CHg wherein R is hydrogen, chlorine or a methyl group, R is hydrogen or an alkyl group, which can have substituted thereon hydrocarbon, hydroxy, alkoxy, aryloxy, aralkoxy, alkaryloxy and acyloxy radicals, n is a Whole number, and Z is a divalent radical with at least two carbon atoms between said valencies and is selected from the class consisting of alkylene, arylene, and alkylenearylene groups which can have substituted thereon hydrocarbon, hydroxy, allroxy, aryloxy, alltaryloxy, aral- Kerry, and acyloxy radicals, as well as additional groups of the formula R CH:=( J-(CR"2)o- O wherein R, R" and u are as indicated above.

While (CR" in the above formula is a repeating unit, it is actually intended that R" can be difierent in each case so that the carbon is the repeating part of the unit and each time each R" can be hydrogen or one of various alkyl groups. For example, in the same compound in one R" group, the R" can be hydrogen in both cases, so as to give --CH in another group one R" can be H, and the other can be CH so as to give the radical another (CR" can have both R" s as methyl groups so as to give the radical in another group one R" can be an octyl group and the other R be a nonyl group so that the radical in that case will be etc. The overall (CR" group, as well as any aliphatic portion of 2, can contain unsaturation.

The length of an aliphatic group in the polyether can be unlimited, regardless of whether the length of the aliphatic chain results from having either or both ns be a large number, or by having R in either or both cases be a long aliphatic chain, or by having Z consist of a long aliphatic chain. Moreover, the radical on one side of the central portion Z can differ from the radical on the other side of the central portion Z even though most of the illustrations herein show similar radicals on the two sides.

Such polyunsaturated polyethers can be derived by forming the others of unsaturated alcohols such as vinyl, isopropenyl, alpha-chloro-vinyl, allyl, methallyl, alphaphenethyl-allyl, beta-chlorallyl, alpha-phenyl-allyl alcohols, 7 hydroxy octene 1,7 hydroxy 2 methyloctene 1; 3 hydroxy 3 methyl butene 1, penten- 1 ol 5, 2,5 dimethyl 5 hydroxy hexene 1,17- iydroxy octadecene 1,5 acetoxy 7 hydroxyoctene 1, 5 phenoxy 7 hydroxy octene 1, etc., with polyhydric compounds of the formula HOZ-OH, with Z defined as above. 7

Examples of various polyhydric compounds from which the polyethers can be prepared are ethylene glycol, trimethylene glycol, 2,3 dihydroxybutane, 1,4 dihydroxybutane, 1,3 dihydroxy 2 phenyl butane, 1,6- dihydroxy hexane, 1,8 dihydroxy octane, 2,11 dihydroxy dodecane, 2,11 climethyl 2,11 dihydroxydodecane; 2,2 dimethyl propanediol 1,3, 3 methylpentanediol 1,4, 2,2 diethylbutanediol 1,4, 4,5,- dihydroxynonane, pentamethylene glycol, heptamethylene glycol, nonamethylene glycol, decamethylene glycol,

glyceryl rnonoacetate, glyccryl monobenzoate, resorcinol,

hydroquinone, catechol, dihydroxymethylnaphthalene, dihydroxy vinyl naphthalene, 2,11 dihyclroxy do? decane 6, 2,11 dihydroxy 6 vinyl dodecane, 2,34- dihydroxy lycopene, dlhYdlOXY-GllllYl naphthalene, dihy droxy-ethoxy naphthalene, dihydroxy-diphenyl, dihydroxy phenethoxy diphenyl, (ethylphenyl)-hydroquinone, (ethylphenoxy) resorcinol, Z-phenoxypropane- 1,3 diol, beta ethylol hydroxy diphenyl, gammahydroxypropylphenol, 2 hydroxy 8 phenylol-nonane, 2,8 dihydroxy 4 phenylnonane, dihydroxy toluene, dimethylol' benzene, di (beta ethylol) ben zene, di-(alpha-ethylol)-benzene, di-(beta-ethylol)-naphthalene,- bisphenol or 2,2-di-(p-phenylol)-propane, betaethylol-phenol, beta-ethylol-naphthol, omega-hydroXy-noctyl-phenol, n-octyl-resorcinol, alpha-methyl-heptyl-resorcinol, sec-butyl-resorcinol, ethoxy-resorcinol, 1,8-dihydroxy-4-acetoxy-octane, phenoxy resorcinol, beta phenylethoxy-hydroquinone, (ethylphenoxy)-catechol, acetoxydihydroxy naphthalene, benzoxy resorcinol, octoxy-bisa a? phenol, etc. Except for practical limitations of availability, there is no upper limit to the number of carbon atoms between the hydroxy groups, particularly when Z is aliphatic since irradiation can cause crosslinking through that part of the molecule.

Polyunsaturated polyethers which can be used in the practice of this invention include the following as examples: the divinyl diethers of ethylene glycol, trimethylene glycol, pentarnethylene glycol, hexamethylene glycol, 2,3-dihydroxybutane, 1,4-hydroxybutane, 1,4- dihydroxy-phenylbutane, resorcinol, di-(beta-ethylol)- benzene, and the other divinyl diethers of the various polyhydric compounds listed above; the diallyl diethers of the various polyhydric compounds listed above, such as the diallyl diether of ethylene glycol, trimethylene glycol, tetramethylene glycol, 2,3-dihydroxybutane, resorcinol, beta-ethylol phenol, bisphenol, etc; the diisopropenyl diethers of the aforementioned polyhydric compounds, such as the diisopropenyl diether of ethylene glycol, trimethylene glycol, tetramethylene glycol, 1,6- clihydroxy hexane, trihydroxy benzene, trimethylol benzene, etc; dimethallyl diethers of ethylene glycol, trirnethylene glycol, pentamethylene glycol, resorcinol etc.; diethers of 2-methylol-butadiene-l,4 and of 2- hydroxy-Z-methyl-octadiene-4,7 with dihydroxy naphthalene, dihydroxy toluene, beta-ethylol-phenol, ethoxy resorcinol, etc; the di-(alpha-chloro-vinyl) diether of 1,8-dihydroxy-octane, the ethylene glycol diether of 7 hydroxy-2-methyl-octene-l, the diether of beta-ethylolphenol and 3 hydroxy-3-methyl-butene-1, the ethylene glycol diether of l7-hydroxy-octodecene-1, the decar'nethylene glycol diether of pentene-l-ol-S, the diether of garnma-hydroxy-propyl-phenol, and -phenoxy-7-hydroxy-octene-l, the diether of alpha-phenethyl-allylalcohol and beta-ethylol-hydroxy-diphenyl, the diether of dihydroxy-phenoxy-naphthalene and 5-phenoxy-7- hydroxy-oc cue-1, etc., as well as corresponding triethers such as trivinyl, triisopropenyl, triallyl triethers of 2,5,7- trihydroxy-noctane, trihydroxy benzene, trimethylol benzene, trihydroxy naphthalene, etc., divinyl diethers of benzoxy-resorcinol, phenethyl-resorcinol, acetoxyresorcinol, propyl-resorcinol, propoxy-resorci'nol, etc., diallyl diethers of l,3=dihydroxy-3-phenylbutane, S- ethoxy 2,7 dihydroxy-n-octane, (beta=hydroxy-ethyl)'- ph-enyl, phenol, etc.

From the results of this invention, it is apparently advantageous to have the unsaturated groups separated from each other to a greater degree than exists in such materials as divinyl ether and alkyl methacrylate which latter materials do not give the eflective results produced by the present invention. It is preferred that there be at least six carbon atoms separating the unsaturated groups.

The use of modifiers having a high proportion of oxygen in the chain between the unsaturated groups such as with modifiers prepared from polyethylene glycols is undesirable. Thus the use of the diacrylate or the divinyl ether of hexaethylene glycol results in decomposition, discoloration, odor and taste'upon irradiation. Such changes are objectionable in many of the uses to which the irradiated product is to be put.

Methods for the preparation of the polyunsaturated polyethers of the type indicated herein are well known in the art. For example, the polyhydroxy compounds or the desired structure can be reacted with po-lyhydric compounds of the types indicated above in accordance with common techniques for producing unsaturated ethers. For vinyl ethers, vinylacetate is used in accordance with known procedures for making vinyl ethers. In many cases it might bepreferable to use the corresponding chloro derivative instead of the hydroxy compound for either the unsaturated alcohol or the polyhydric compound, together with stoichiometric amounts or alkaline material such as NaOH to promote ether forination according to well known procedures. In view of the tendency of many of the unsaturated alcohols to polymerize, polymerization inhibitors are advantageously used during the reaction. In some cases the cthers are advantageously prepared by reacting sodium alcoholates or phenolates, etc., with chloro compounds such as, for example, disodium resorcinolate with 8-chloro-nonene-2.

in view of the great tendency of said polyunsaturated polyethers to polymerize, it is most surprising to find that these compounds react to crosslinlr the polymeric oleiins instead of forming homopolyrners themselves which would be heterogeneously dispersed in the polymeric olefin. 7

It has been found, in accordance with this invention, that comparable or higher degrees of crosslinking can be effected in the polymers with lower irradiation doses in the presence of polyunsaturated modifiers than is effected on the polymers not containing such modifiers. Furthermore, polymers irradiated without these modifiers are more brittle and stiffer than polymers irradiated with these modifiers.

The linear, saturated aliphatic polyesters used in the practice of this invention can advantageously be prepared from dihydroxy alkanes, such as ethylene glycol, and dicarboxylic aliphatic acids, such as succinic acid, or from aliphatic compounds containing an hydroxy and carboxylic acid group in the same molecule. While the dihydroxy and dioarboxylic compounds are advantageous in the preparation of linear polyesters, it is possible and very often desirable to use other polyhydric allianes and other polycarboxylic aliphatic acids in quantities or under conditions which give polymers which are not substan tially cro-sslinlred. For example, glycerine can be used in such amounts or under conditions controlled so as to give very little or no crosslinking. Thus succinic acid or anhydride can be reacted with less than the stoichiometric amount of ethylene glycol. Then, when the esterification reaction is substantially completed, glycerine can be added in such a calculated amount that only two hydroxy groups oi the glycerine can enter the reaction to complete esterification with the free carboxylic acid groups in the reaction mixture. Furthermore, polyhydric and polycarboxylic aliphatic compounds of the type indicated can be partially esterified so that there are substantially only two hydroxy or carboxylic acid groups available to participate in the polymerization reaction. Thus, the monostearate of glycerine, or the dicaproate of pentaerythritol, or the monohexyl ester of tricarballylic acid can be used;

Methods of preparing the polyesters are well known in the art. The acids and the glycols, or the hydroxy acids, can be used in these preparations, or where desirable or 'advantageous various derivatives, such as the esters, anhydrides, acid chlorides, etc., can be used.- Generally, for high molecular weight polysters it is neces-' sary or desirable to conduct the esterification under reduced pressures.

It has been noted that polymers having molecular weights greater than about 6,000 can easily be converted to insoluble products in accordance with the practice oi this invention. With polymers of lower molecular Weight, it is necessary to expose them to correspondingly greater amounts of irradiation to reach the insoluble stage. However, it is contemplated that irradiation treatment of such lower molecular weight polymers for other purposes as described hereinafter, for example 3,000 and even lower, is within the scope of this invention, even though the irradiation is not carried on far enough to effect insolubility. For such lower molecular weight polymers a considerable amount of the preliminary irradiation apparently is directed to increasing linear polymer chains, or in changing the type of polymer linkage. After the linear polymer length has reached a certain amount or type, the joining together of polymer chains apparently results in the crosslinking which eltects insolubility. It is also possible that there is a certain amount of decomposition.

linking of polymer chains, and thereby improvement of 7 properties as above noted, than is the case when the polymers are irradiated in the absence of these polyunsaturated modifiers. Furthermore, there is less side reaction, such as degradation and discoloration, when these modifiers are used.

For most purposes in the practice of this invention it is genera ly desirable to have the polyester molecules a higher proportion of methylene or -CH groups, or of hydrocarbon port-ion than ester or --COO-- groups. While most or" the polyesters shown above are of the more easily available hydroxy and carboxylic acid compounds having a relatively few number of carbon atoms between the esterifiable groups, there is no limitation on the number of carbon atoms which separate the este-r-ifiable or csterified groups. This is determined by the properties desired in the resultant polyesters, the availability of the materials and the sluggishncss of such high molecular weight materials to undergo esterification because of the higher proportion of non-esteririable portions of such materials.

Various hydroxy and carboxylic acid compounds can be used in various combinations of two or more in the preparation of polyesters as indicated herein suitable for the practice of this invention including, but not limited to the following: ethylene glycol, trimethylene glycol, tetramethylene glycol, pentamethylene lycol, hexamethylene glycol, 2,2-dimethylpropanediol-1,3, 3-methylpentanediol-l,4, 2,2-diethylbutanediol-1,4, 4,5-dihydroxy-nonane, heptamethylene glycol, nonamethylene glycol, decamethylene glycol, 3-methylpentanediol-l,5, sebacic acid, azelaic acid, adipic acid, succinic acid, octylsuccinic acid, succinic acids produced by the hydrogenation of condensation products of maleic anhydride with C and similar oleiins, malonic acid, methylmalonic acid, methyl succinic acid, brassilic acid, glutaric acid, pimelic acid, sub-eric acid, japa -ic acid, thapsic acid, etc. l-iydroxy aliphatic carboxylic acids which can also be used, either alone, in mixtures of two or more with each other, or in mixtures of glycols and polybasic acids to produce esters tor the practice of this invention include, but are not restricted to: omega-hydroXy-decanoic acid, beta-hydroxyisobuteric acid, epsilon-hydroxycaproic acid, hydroacrylic acid, sabinic acid, juniperic acid, jalapinolic acid, etc.

The polymers can be in any suitable form for admixing with, or absorbing, or containing the polyunsaturated modifier. For e3: le, it can be in powder, film, fiber, pellet or solution form, so as to present large areas for absorbing or contacting the modifier. Molded articles can also be so treated. if desired, increased temperatures can be used provided the modifier does not thermally polymerize to an undesirable extent at those temperatures.

i the modifier is in liquid or solution form, the admixture can be performed by absorption. For example, the polymers are allowed to stand in the modifier in liquid or solution form until 'a desired amount has been absorbed or diihised therein. This amOuut can be determined by periodically removing the polymers, draining or wiping ed the excess liquid and weighing to determine the amount absorbed. Sometimes it may be desirable to allow the so-treated polymers, particularly the more massive structures, to stand for a time sufficient to permitdiffusion of the absorbed material to give more uniform distribution throughout the mass of .the polymers.

However, the modifier can be introduced in any other convenient or appropriate manner. For example, the mixture can also be effected mechanically as on mixing mills, in a Banbury mixer, or in a single or double worm extruder. Since the heat generated in such latte-r types of mixing may cause polymerization of the modifier, particularly where the latter is very actively polymerizable, this type of mixing is very often best carried out at reduced temperatures, in the presence of an inert atmosphere, such as nitrogen, and/or in the presence of a polymerization inhibitor, such as 2,G-ditertiary-butyl-paracresol, tertiary-butyl-catechol, etc. Such compounded mixtures can then be extruded as fibers, films, rods, etc, or as wire coatings or coatings on fibrous materials for clotheslines, etc., and then irradiated. They can also be extruded in tubular form, such as pipes, molded into shaped articles, or blown into bottles, and in each case then irradiated.

The term irradiation, as used herein, means high energy radiation and/or the secondary energies resulting from conversion of this electron energy to neutron or gamma radiation, s d electron energies being at least about 100,000 electron volts. While various types of irradiation are suitable for this purpose, such as X-ray and gamma and beta rays, the radiation produced by high power electron linear accelerators has been found to be very conveniently and economically applicable and to give very satisfactory results. However, regardless of the type of irradiation and the type of equipment used for its generation or application, the use thereof in the treatment of polymeric materials as described herein is contemplated as falling within the scope of this invention so long as it is produced by or from electron energy of at least about 100,000 electron volts. While there is no upper limit to the electron energy that can be so applied advantageously, the effects desired in the practice of this invention can be accon p-lished without having to go above 50,000,000 electron volts. Generally, the higher the electron energy used, the greater is the depth of penetration into the massive structure of polynieri materials, and the shorter is the time of exposure required to accomplish the desired result. For other types of irradiation, such as gamma and X-rays, energy systems equivalent to the above range of electron volts are desirable. y

it is intended that the term irradiation include What been referred to in the prior art as ionizing radiation which has been defined as radiation possessing an energy at least sufficient to produce ions or to break chemical bonds and thus includes also radiations such as ionizing particle radiation as well as radiations of the type termed ionizing electromagnetic radiation.

The term ionizing particle radiation has been used to designate the emission ofelectrons or highly accelerrated nuclear particles such as protons, neutrons, alphaparticles, deuterons, beta-particles, or their analogs, directed in such a way that the particle is projected into the mass to be irradiated. Charged particles can be accelerated by the aid of voltage gradients by such devices as accelerators with resonance chambers, Van de Graaii generators, betatrons, synchrotrons, cyciotrons, etc. Neutron radiation can be produced by bombarding a selected light metal such as berylliurnwith positive par- .ticles of high eneregy. Particle radiations-can also be obtained by the use of an atomic pile, radioactive isotopes or other natural or synthetic radioactive materials.

ionizing electromagnetic irradiation is produced when a metallic target, such as tungsten, is bombarded with electrons of suitable energy. This energy is conterred to the electrons by potential accelerators of over 0.1 million electron volts (mev.). In addition to radiations of this type, commonly called X-ray, an ionizing electromagnetic radiation suitable for the practice of this invention can be obtained by means of a nuclear reactor (pile) or by the'use of natural or synthetic radioactive material, ior example cobalt 60.

Varioustypes of high power electron linear accelera- 7 tors are commercially available, for example from Ap plied Radiation Corporation, Walnut Creek,.California.. In the following Example I, ARCO type travelling wave accelerator, model Mark 1, operating at 3 to 10 million electron volts, was used to supply the irradiation. Other types of accelerators, such as supplied by High Voltage. Engineering Corporation, Burlington, Massachusetts, or as described in United States Patent No. 2,763,609 and in British Patent No. 762,953 are satisfactory for the practice of this invention.

In the following examples, the radiation doses are rcported in megareps, which represent 1,000,000 reps. A rep is defined, according to Reactor Shielding Design Manual, edited by Theodore Rockwell ill and published by D. Van Nostrand Company, Inc., 1st edition, 1956,. as Lot radiation dosage which produces energy absorption in human tissue equal to 93 ergs per gram of tissue.

in the practice of this invention, changes in properties of the polymeric materials can often be noted after -reatment with even less than 1 megarep. However, it is generally advantageous to use doses of 2 megareps or more. The degree of change in properties is dependent somewhat on the dosage, greater changes being effected by increasing the dosage.

The polymer material to be treated is often advantageously irradiated while in a container made of a material such as aluminum or glass which will not substantially interfere with the irradiation. It is advantageous also to use polymeric materials, such as polyethylene itself, nylons, i.e. 66 nylon, polycaprolactam, etc. It can also be wrapped in film or foil impervious to vapors and gases, such as aluminum foil, polyethylene film, etc., which will prevent substantially the escape of volatile materials. it is often advantageous to avoid oxidation or side reactions by the use of an inert atmosphere such as nitrogen. Moreover, it is advantageous to prevent the temperature from approaching that at which the polymer material is unstable. This can be accomplished by cooling the polymer material before irradiation, for example with Dry ice, or by dissipating the heat generated during irradiation.

Various methods of practicing the invention are illustrated by the following examples. These examples are intended merely to illustrate the invention and not in any sense to limit the manner in which the invention can be practiced. The parts and percentages recited therein and all through this specification, unless specifically provided otherwise, refer to parts by weight and percentages by weight. Unless indicated otherwise, the terms polymers and polymeric are intended to include copolymers and copolymeric. Molecular weights given herein are Staudinger molecular weights.

EXAMPLE I A polyester prepared from ethylene glycol and sebacic acid having a molecular weight of 6,000 and being completely soluble in chloroform, is mixed intimately on a Banbury mixer with 5 percent of divinyl ether of hexamethylene glycol. The resulting mixture is divided into a number of samples which are individually wrapped in aluminum foil and given different amounts of irradiation using a high power electron linear accelerator of the following dosages: 5, 10, 25, 50 and 100 megareps respectively. In each case the irradiated product is infusible and insoluble in chloroform, and is less stiff and less brittle than the same polyester irradiated in the absence of the polyunsaturated modifier.

Various samples of this same polyester, similarly treated with the polyunsaturated modifier, are exposed to 1x10 roentgens each of gamma radiation, X-rays, neutron radiation from bombarded beryllium, radiation from radioactive cob-alt 60, and radiation from a Van de Graaif generator. In each case similar improvements of propertiesare noted.

EXAMPLE II A polyester prepared from trimethylene glycol and azelaic acid, which has a molecular weight of 10,000 and is completely soluble in chloroform is treated according to the procedure of Example 1 and similar improvements with respect to stiffness, brittleness, and solvent and heat resistance are noted.

EXAMPLE Ill 7 A polyester prepared from tetramethylene glycol and adipic acid, which has a molecular Weight of 8,000 and is completely soluble in carbon tetrachloride is mixed on a Banbury mixer with 8 percent of the diallyl ether of ethylene glycol. Upon treatment of Various samples with 5 megareps, 25 megareps, and 50 rnegareps respectively of irradiation as in Example I, the product is found in each case to be insoluble in carbon tetrachloride, chloroform, and me.hylene dichloride, is infusible, and is improved with respect to stiffness and brittleness over the same polyester irradiated without the polyunsaturated modifier.

EXAMPLE IV A polyester prepared from pentamethylene glycol and succinic acid anhydride, which has a molecular Weight of 12,000 and is completely soluble in chloroform, is divided into powder form, mixed on a mill with 2 percent by weight of the divinyl ether of pentamethylene glycol and then extruded into pellets. Samples of these pellets are individually wrapped in polyethylene film and exposed to 5, i0 and 50 megareps of irradiation respectively, in accordance with the procedure of Example i. In each case the irradiated product is insoluble in chloroform and is infusi'ole.

EXAMPLE V A polyester prepared from omega-hydroxy-decanoic acid, having a molecular weight of 6,000 and being completely soluble in chloroform, is mixed in powder form on a mill with 5% octamethylene divinyl ether and then extruded in a thin sheet. Samples of this sheet are individually wrapped in aluminum foil and exposed to 15, 25 and 35 megareps of irradiation respectively in accordance with the procedure of Example I. In each case the irradiated product is insoluble in chloroform, is infusible, and is improved with respect to stiifness and brittleness over the same polyester irradiated without the polyunsaturated modifier.

EXAMPLE VI Glycols:

A2,2-Dimethylpropanediol-1,3 B--3-Methylpentanediol-l,4 C4,5-Dihydroxynonane D-Decamethylene glycol E-Tetramethylene glycol F-3-Methylpentanediol-1,5 GHexamethylene glycol H-Ethylene glycol Dibasic Acids:

K-Sebacic acid LAzelaic acid -M-Br-assilic acid N-Octylsuccinic acid -Succinic acid P-Pi1nelic acid Q-Adipic acid RHydrogenated condensation product of C olefin and maleic anhydride Modifier:

S-Divinyl ether of l,4-dihydroxybutane T-Diallyl ether of bis-phenol UDiisopropenyl ether of di-(beta-ethylol)-benzene V-Dimethallyl ether of dihydroxy toluene W-Di-(chlorallyl) ether of 1,8-dihydroxy octane X-Glycery1 diether of 8-vinyl-octane-1-o1 YDiallyl ether of hexamethylene glycol in addition to the foregoing modifiers, other materials may be present in minor amounts in the polymeric compositions, added by various Well-known means, such as milling, etc. Thus, for example, plasticizers, lubricants, fillers, etc. can be added .in accordance with the eiiects desired. Suitable fillers are silica, silica aerogel, titanium dioxide, calcium silicate, ferric oxide, chromic oxide, cadmium sulfide, asbestos, glass fibers, calcium carbonate, carbon black, lithopone, talc, etc. Furthermore various modifications and improvements in properties can be offected by admixing these polymeric materials with various other resins regardless of Whether such other resins are degraded when irradiated by themselves. Even if so degraded, the crosslinking'produced by irradiation with polymeric materials as in this invention results in various novel improvements in the polymeric materials. Such other resins include: polyacrylic esters, polystyrene polyethylene, chlorinated polyethylene, chlorosulfonated polyethylene, natural and synthetic rubbers, butadieneacrylonitrile copolymers, neoprenes, polydimet-hylsiioxanes, styrene-acrylonitrile copolymers, polymethyl methacrylate, polyvinyl chloride, polyvinylidene chloride, polytetrafiuoroethylene, polychlorotrifiuoroethylene, cellulose, polyisobutylene, etc.

An important feature of this invention resides in the fact that the irradiated product can be hydrolyzed or saponified, according to any of the well-known procedures for saponification, to give various polytunction-al prod ucts. For example, compounds having a plurality of functional groups can be prepared. Thus, representing par-ts of various polymeric molecules used herein, With Z representing a crosslinlring residue of the polyunsaturated modifier, possible products obtained upon hydrolysis or saponificatio-n can be illustrated as follows:

A and B both represent segments'of two polyester molecules in which R and R are divalent hydrocarbon groups as indicated above for the linear, aliphatic, saturated polyesters. Where the two molecules are crosslinked through the R groups, hydrolysis will produce a trihydroxy compound. Similarly, Where the crosslinkage isthrough the R groups, hydrolysis produces a monohydroxy-dicarboxylic acid.

Accordingly, where the polyethylene glycol sebacatedivinyl ether of hexamethylene glycol irradiated product of Example I is used andthe crosslinkages are as in A and B, then the saponification products include trihydroxybutane and ethylol sebacic acid.

Where the present invention is practiced only for the purpose of making derivatives by the hydrolysis of the irradiated product, then the modifier can also be a compound having only one unsaturated group of the type indicated for the polyunsaturated modifier. For example, monoalkenyl esters can be used such as vinyl butyl other, allyl ethyl ether, isopropenyl phenyl ether, vinyl ethyl diether of ethylene glycol, etc.

Such saponification products can be represented generally by the following formulas with the various symhols as previously indicated:

and

.Hooc-a r COOH l "*CH2 (CR"2)01;OH

J Accordingly, the saponification products of irradiated polyethylene glycol sebacate-divinyl ether of hexamethylene glycol are represented by the formulas:

With polymer segments C and D where the cross linkage is shown between an R and an R group, the product upon hydrolysis includes both a trihydroxy compound and a monohydroXy-dicarboxylic acid compound, such as represented by the formulas of the two preceding paragraphs.

With polymer segments E and F representing parts of a polyester made from an hydroxycarboxylic acid, the hydrolysis product is a trihydroxyqnonocarboxylic acid. Accordingly when the irradiated product of Example V is used, the saponification products include trihydroxymonocarboxy-undecane.

Such saponification products can be represented generally by the following formula with the various symbols as previously indicated Therefore, it can be seen that the foregoing permits the production of various polyfunctional hydroxy and carboxylic acid compounds. This is surprising and especially important in view of the fact that when the corresponding monomeric hydroxy and carboxylic acid compounds are irradiated directly, the monomers generally decompose and do not give the polyfunctional derivatives illustrated above. It is not intended, however, that the invention be restricted to the specific type of products, or linkages, or theories indicated above. it is contemplated that the invention covers whatever products are obtained by the practice taught herein regardless of the exact chemical structure. The foregoing is merely illustrative of the possibilities of the invention.

The hydrolysis can be carried out on any of the irradiated resins produced according to any of the fore going examples. A suitable procedure is illustrated by the following examples:

EXAMPLE VII Potassium hydroxide is dissolved in alcohol-the amount of KOH being slightly in excess of the stoichiometric amount calculated on the basis of the amount of resin to be hydrolyzed. The resin advantageously in powder or flake form and the alcoholic solution are placed in equipment provided with stirrer and reflux condenser. The mixture is stirred and refluxed for about half an hour after the resin has gone into solution. The resultant solution contains the hydroxy derivatives and the potassium salt of the carboxylic acids. The solution is concentrated by distilling oii some of the alcohol and the hydroxy and carboxylic acid derivatives separated by various means such as neutralization, distillation, crystallization, extraction, etc.

EXAMPLE VIIl When the irradiated resins of Examples i-Vl inclusive are individually hydrolyzed by the procedure of the preceding example and sufiicient hydrochloric acid added in each case to react with the potassium present in the product, followed by atmospheric distillation of the volatile materials present and subsequent distillation at reduced pressure, distillates of wide boiling range are obtained in each case. Various fractions of these distillates give tests indicating the presence of hydroxy and carboxylic acid groups.

The compositions produced according to the preceding two examples are particularly useful in the preparation of modified drying oil compositions, wetting agents, detergents, sequestering agents, etc., and are used in the manner in which such products are generally used. As indicated previously herein the irradiated polymeric materials produced by the invention disclosed herein, including those containing various modifiers as described, are useful in the production of textile fibers, packaging films, protective coatings and other shaped articles of improved properties, such as improved heat and solvent resistance, which fibers, films, etc. are advantageously used for the purposes and in the manner in which such products are generally used.

The amount of polyunsaturated modifier to be added will vary depending on the properties desired in the ultimate product. As would be expected, the greater the amount of such compound used, the greater is the change in properties of the irradiated product. Although even as little as 0.1 percent of polyunsaturated compound often effects notable changes in properties, it isgenerally advantageous to have at least one percent or more of such modifiers present. There is no upper limit to the proportion of such compound that may be present. However, when there is more than fifty percent present, the properties of the products approach those of polymers obtained by irradiation of the modifiers alone. Therefore, to retain characteristics of the polymeric olefin, it is desirable to have no more than fifty percent by weight of the modifier. However, in cases where the irradiated product is to be saponified for recovery of the type of products indicated herein, the proportion of modifier is adjusted accordingly to the yield desired for such products, and, especially in cases Where the molecular weight of the polyunsaturated modifier is considerably more than the molecular weight of the polymer unit which will be liberated by saponification, then it may be desirable to have greater proportions than fifty percent by weight of the modifier present.

While certain features of this invention have been described in detail with respect to various embodiments thereof, it will, of course, be apparent that other modifications may be made within the spirit and scope of this invention and it is not intended to limit the invention to the exact details shown above except insofar as they are defined in the following claims.

The invention claimed is:

1. A process for producing improved polyester resin compositions comprising the treatment of a linear, saturated aliphatic polyester having ester groups in the linear polymer chains thereof, having at least two carbon atoms between ester groups in the polymer molecule with at least about 2 megareps of high energy, ionizing radiation equivalent to at least 100,000 electron volts while said polyester is in intimate and substantially uniform mixture with at least 0.1 percent by weight, based on the weight of polyester resin, of a polyunsaturated compound of the formula If R CHz=O-(C11!)m-0ZO(GR"2)m'J=OH; wherein each R is respectively selected from the class consisting of hydrogen, chlorine and methyl groups, each R" is respectively selected from the class consisting of hydrogen, alkyl groups and akyl groups having hydrocarhon, hydroxy, alkoxy, aryloxy, alkaryloxy, aralkoxy and iacyloxy substituents thereon, in and m are values selected from the class consisting of zero and integers, and Z is a divalent radical with at least two carbon atoms between said valencies and is selected from the class consisting of divalent alkylene, arylene, alkylene-arylene groups and the hydrocarbon, hydroxy, alkoxy, aryloxy, alkaryloxy,

aralkoxy, acyloxy and derivatives thereof, wherein R, R" and m are as indicated above.

2. A process of claim 1, in which at least 1 percent of said polyunsaturated compound is used.

3. A process of claim 2, in which the irradiated prod uct is subsequently saponified.

4. A process of claim 1, in which said polyunsaturated compound is derived from an alkylene glycol.

5. A process of claim 1, in which said polyunsaturated compound is derived from an alkylene glycol having at least six carbon atoms between the hydroxy groups.

6. A process of claim 5 in which said polyunsaturated compound is a divinyl other.

7. A process of claim 6 in which at least 1 percent of the divinyl ether is used.

8. A process of claim 5 in which said polyunsaturated compound is a diallyl ether.

9. A process of claim 1 in which said polyunsaturated compound is a diisopropenyl ether.

10. A process of claim 1 in which said polyunsaturated compound is a dirnethallyl ether.

11. A process of claim 1 in which said polyester is derived from a dihydroxy all-lane and a dicarboxylic alkane.

12. A process of claim 1 in which said polyester is derived from polymeric ethylene glycol sebacate.

13. A process of claim 1 in which said polyester is derived from polymeric tetr-amethylene glycol adipate.

14. A process of claim 1 in which said polyester is derived from polymeric hexamethylene glycol adipate.

15. A process of claim 1 in which said polyester resin is prepared from an hydroxy alkanoic acid.

'16. A process of claim 1 in which said polyester is derived from omega-hydroxy-decanoic acid.

'17. A process of claim 1 in which said polyester has a molecular weight of at least 3,000.

References Cited in the file of this patent UNITED STATES PATENTS 14 Caldwell July 15, 1958 Banes et a1. Dec. 2, 1958 Schmitz et al Ian. 12, 1960 FOREIGN PATENTS Great Britain Sept. 17, 1952 Canada Ian. 26, 1954 France May 19, 1954 France Dec. 12, 1955 (4th addition to No. 1,079,401)

OTHER REFERENCES Ballantine et aL: Brookhaven National Laboratory Report No. 389, pp. 611, May 1956.

Synthetic High Polymers, pp. 173-176 (1958). 

1. A PROCESS FOR PRODUCING IMPROVED POLYESTER RESIN COMPOSITIONS COMPRISING THE TREATMENT OF A LINEAR, SATURATED ALIPHATIC POLYESTER HAVING ESTER GROUPS IN THE LINEAR POLYMER CHAINS THEREOF, HAVING AT LEAST TWO CARBON ATOMS BETWEEN ESTER GROUPS IN THE POLYMER MOLECULE WITH AT LEAST ABOUT 2 MEGAREPS OF HIGH ENERGY, IONIZING RADIATION EQUIVALENT TO AT LEAST 100,000 ELECTRON VOLTS WHILE SAID POLYESTER IS IN INTIMATE AND SUBSTANTIALLY UNIFORM MIXTURE WITH AT LAST 0.1 PERCENT BY WEIGHT, BASED ON THE WEIGHT OF POLYESTER RESIN, OF A POLYUNSATURATED COMPOUND OF THE FORMULA 